From e62485f489769af3cc35139170d217c674c60971 Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Tue, 29 Dec 2015 19:10:36 +0100 Subject: more functions to add + implement readn, writen, preadn, and pwriten MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- src/unistd/readn.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 src/unistd/readn.c (limited to 'src/unistd/readn.c') diff --git a/src/unistd/readn.c b/src/unistd/readn.c new file mode 100644 index 0000000..b50abe5 --- /dev/null +++ b/src/unistd/readn.c @@ -0,0 +1,73 @@ +/** + * slibc — Yet another C library + * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ +#include +#include + + + +/** + * Variant of `read` that will read until the request + * amount of that has been read, or there is no more + * data to read. This function will block signals so + * that it cannot throw `EINTR`, which could mean that + * read data is lost. Note however, it may fail for + * any other reason resulting in lost data. + * + * This is a Plan 9 from Bell Labs compliant slibc extension. + * + * @etymology (Read) all `(n)byte` bytes! + * + * @param fd The file descriptor whence the data shall be read. + * @param buf The buffer whither the read data shall be stored. + * @param nbyte The number of bytes to read. + * + * @throws Any error specified for read(3), except `EINTR`. + * + * @since Always. + */ +ssize_t readn(int fd, void* buf, size_t nbyte) +{ + char *buffer = buf; + ssize_t r, n = 0; + sigset_t mask, oldmask; + int saved_errno = 0; + + sigfillset(&mask); + sigprocmask(SIG_BLOCK, &mask, &oldmask); + + while (nbyte) + { + r = read(fildes, buffer, nbyte); + if (r < 0) + goto fail; + if (r == 0) + break; + n += r; + nbyte -= (size_t)r; + buffer += r; + } + + sigprocmask(SIG_SETMASK, &oldmask, NULL); + return n; + fail: + errno = saved_errno; + sigprocmask(SIG_SETMASK, &oldmask, NULL); + saved_errno = errno; + return -1; +} + -- cgit v1.2.3-70-g09d2